Cold cores trace hidden regions of star formation and thus the earliest stages of this process. Planck (see also their mission blog) allows cold cores to be found and Herschel can then follow them up. Planck should be able to produce an unbiased catalog of >>1000 cold cores.

Not much can be said about the Planck results at the moment, but the Planck First Light Survey has produced some sources for followup. 3 fields observed, showing lots of detail of these enigmatic sources. Two are associated with ongoing star formation but one is quiescent. Dust temperatures as low as 10-13K are found.